Update projects_enforcing_code_owner_approval descriptions

ee/config/metrics/counts_28d/20210216182043_projects_enforcing_code_owner_approval.yml

 ---
 data_category: operational
 key_path: usage_activity_by_stage_monthly.create.projects_enforcing_code_owner_approval
-description: Count of total projects that require approval by code owners for code
-  changes
+description: Count of monthly unique users creating projects that require approval by code owners for code changes.
 product_section: dev
 product_stage: create
 product_group: group::source code

ee/config/metrics/counts_all/20210216182019_projects_enforcing_code_owner_approval.yml

 ---
 data_category: optional
 key_path: usage_activity_by_stage.create.projects_enforcing_code_owner_approval
-description: Count of users creating projects that require approval by code owners
-  for code changes.
+description: Count of unique users creating projects that require approval by code owners for code changes.
 product_section: dev
 product_stage: create
 product_group: group::source code